Development of a cyan blue-emitting Ba(3)La(2)(BO(3))(4):Ce(3+),Tb(3+) phosphor for use in dental glazing materials: color tunable emission and energy transfer

The Ce(3+)/Tb(3+) doped Ba(3)La(2)(BO(3))(4) phosphors were synthesized by a conventional solid state reaction method. The synthesized phosphor samples are a single phase of Ba(3)La(2)(BO(3))(4) and showed angular-shaped fine grains with average particle size from 5 μm to 10 μm. The Ba(3)La(2)(BO(3))(4):Ce(3+) phosphors showed an asymmetric broad blue emission under excitation at 365 nm and the Ba(3)La(2)(BO(3))(4):Tb(3+) phosphors exhibited typical green emission assigned to the 4f–4f transition of Tb(3+) under excitation at 254 nm. Under near-UV (365 nm) excitation, Ba(3)La(2)(BO(3))(4):Ce(3+),Tb(3+) phosphors showed both a blue emission band and green emission peaks due to Ce(3+) and Tb(3+), respectively. By optimizing the composition, cyan-blue emission with high color purity (CIE chromaticity coordinate values x = 0.2557 and y = 0.3839) was obtained for the Ba(3)La(2)(BO(3))(4):0.05Ce(3+),0.03Tb(3+) phosphor, and the internal quantum efficiency of the phosphor at the excitation wavelength of 365 nm is estimated to be 50%. The dental glazing paste prepared by mixing organic binder, Ba(3)La(2)(BO(3))(4):Ce(3+),Tb(3+) phosphors, and low T(g) glass was successfully vitrified when it was heated at 600 and 700 °C, and showed high chemical stability of the luminescence properties in acidic aqueous solution (pH = 4).